M85.60 classifies a bone cyst that does not fit the solitary (unicameral) or aneurysmal categories, at an anatomic site that is not specified in the documentation.

Documentation tips

What should appear in the chart to support M85.60.

Source · Editorial brief grounded in 4 cited references ↓

• Record the specific bone involved by name (e.g., proximal humerus, distal femur) — any named site moves the code to a site-specific M85.6x child code and away from M85.60.
• Include the imaging modality and key finding (e.g., 'MRI right tibia demonstrates expansile intramedullary cystic lesion with fluid-fluid levels') to support cyst characterization and rule out aneurysmal or unicameral subtypes.
• Document the cyst type explicitly — 'other cyst of bone' or 'bone cyst NEC' — to distinguish from solitary (M85.4x) and aneurysmal (M85.5x) variants, which bill under separate codes.
• If biopsy or pathology results are available, reference the pathology report date and specimen source so reviewers can confirm the lesion is not a neoplastic process requiring a D-code or C-code instead.
• Note any prior treatment attempts (aspiration, steroid injection, curettage) to support medical necessity when surgical intervention is planned.

Related CPT procedures

Procedure codes commonly billed with M85.60. Linking the right diagnosis to the right procedure is what establishes medical necessity.

Source · CMS LCDs · AAOS specialty guidance · claims-pattern analysis

Common coding pitfalls

The recurring mistakes coders make with M85.60 and adjacent codes.

Source · Editorial brief grounded in CDC ICD-10-CM tabular guidance, AAOS coding references, and cited references ↓

• Defaulting to M85.60 when a site is mentioned anywhere in the record — if the note names even one bone, a site-specific M85.6x code is required and M85.60 will not survive a specificity audit.
• Confusing M85.60 with M85.40 (solitary bone cyst, unspecified site) or M85.50 (aneurysmal bone cyst, unspecified site) — imaging characteristics and pathology distinguish these subtypes; the wrong parent category can trigger a denial.
• Assigning M85.60 for fibrous dysplasia lesions that were initially read as cysts on plain film — fibrous dysplasia routes to M85.00–M85.09, not M85.6x.
• Using M85.60 for congenital or developmental bone cysts, which belong in the Q78.x congenital malformation block, not the M85 acquired disorder block.
• Omitting a secondary code for an underlying condition (e.g., hyperparathyroidism causing brown tumors) when the cyst is a known sequela of a systemic disorder — code the underlying disease first or as an additional diagnosis per ICD-10-CM conventions.

Clinical context

Source · Editorial summary grounded in 4 cited references ↓

Sibling codes

Other billable codes under M85.6 (laterality / anatomic variants).